DEMOGRAPHIC TRAITS OF TWO PHYTOPHAGOUS MITES (TETRANYCHUS CINNABARINUS AND ACULOPS LYCOPERSICI) AND BIOLOGICAL CONTROL ON TOMATO

Tomato production is conducted in Tunisia throughout the entire year. Two species of phytophagous mites: Tetranychus cinnabarinus, the carmine spider mite; and Aculops lycopersici, the tomato russet mite cause important damages in both the greenhouse and in the field. T. cinnabarinus lay an average of 26 eggs during its lifetime at 25°C and 30 eggs at 30°C. Longevity of the females was 12.8 and 9.3 days at 25 and 30°C, respectively. The life cycle was 12.8 days for females and 11.7 days for males at 25°C; while at 30°C, it was 7.2 days for females and 6.2 days for males. A. lycopersici females, on the other hand, laid an average of 18 eggs at 30°C, surviving an average of 17.6 days. Population increases of T. cinnabarinus were observed at Tastour, around mid-June in field tomatoes with the damage threshold quickly reached 15 days later. The virulence peak was observed by mid-July with a maximum of 49 mobile forms/leaf. A. lycopersici generally appeared in fields 15 days after the carmine spider mite, at the beginning of July. One month later, the virulence peak was observed with 78 mobile forms/leaf. A biological control release of P. persimilis was carried out in a test field. Results showed an effective reduction of 79.3% of the initial population of the carmine spider mite population after 15 days. However, this predatory mite needs a latency period for adaptation to the climatic conditions and must be introduced early into the field site before becoming effective.